Binding and attuning an item used to require (minimum level of item ^ 2) Khyber Dragonshard Fragments, so a minimum level 12 item would require 144 fragments. An item that is bound no longer takes permanent item damage when repaired, but permanent damage sustained up to that point cannot be repaired and the item can no longer be traded.

As of April 14, 2012, items that are already BtC require 400 fragments.